Mark wrote:

"Aaron Fude" wrote in message
...
Hi,

What's the point of caulking the roof flashing for the exaust fan
vent?

Specifically, I'm talking about what takes place at 2:20 in the
following video:

http://youtube.com/watch?v=IrwWOW9RE3Q

It seems to be protection against the water flowing up. Is this done
to protect agaist the moisture drawn up by capilary forces? And in
that case, are the shingles themselves caulked?

Thanks!

That looks like a fairly flat roof they are installing on, so my guess
is that they are trying to prevent 'run-under' where the water isn't
necessarily backup UP under the shingles, but running in from the side.


Remember also that strong winds can blow water all
over the place and even
into tiny holes or cracks.